Anchor: U.S. Assistant Secretary of State for East Asia David Stilwell has warned North Korea against taking any "ill-advised" actions amid rising concerns the regime may conduct another nuclear or long-range missile test. The U.S. is also boosting its surveillance of the reclusive state, which has been exposing signs of a possible provocation. 
Kim Bum-soo has more. 

Report: Washington says it will no longer tolerate "ill-advised behavior" by North Korea.  

Speaking at a forum hosted by the Center for Strategic and International Studies in Washington on Thursday, Assistant Secretary of State David Stilwell upgraded the U.S.' warning by a notch.

[Sound bite:  David R. Stilwell - US Assistant Secretary of State for East Asian and Pacific Affairs] 
"Threats are threats. We’ve heard threats before. Whether they actually carry those threats out in light of where the President has said he wants to go; he wants to work with North Korea, he wants to help build their economy. But there’s also the reminder that we can’t have any more of this unfortunate, ill-advised behavior and that hasn’t changed, that position is still the same." 

North Korea has been showing signs that it may be working on a long-range rocket launch.

Recent commercial satellite imagery suggests increased activity at the North's key Sohae launch site. Amid this, the U.S. has been boosting aerial surveillance over the Korean Peninsula. 

[Sound bite: Rear Admiral William Byrne - Vice Director of the US Joint Staff]  
(Reporter: Are you seeing any signs that North Korea is preparing any kind of nuclear or any kind of missile test?)  
"Well in an open forum, I’m not going to share any classified information, obviously and we don’t talk about specific indications and warnings...."   

During a Pentagon news conference, vice director of the U.S. Joint Staff William Byrne noted that his military cannot rely on a wishful thinking. 

[Sound bite: Rear Admiral William Byrne - Vice Director of the US Joint Staff] 
"The North Koreans have made a commitment to denuclearize and to cease their long-range missile testing and their nuclear weapons testing. And we would hope that they would abide by those words, but hope is not a strategy. As the secretary said up on Capitol Hill yesterday, we hope for the best and we plan for the worst." 

[Sound bite: Flight test of prototype inter-mediate ballistic missile (Dec. 12 Vandenberg Air Force Base, California)]

In another possible warning, the U.S. on Thursday fired a new intermediate-range missile that can potentially strike deep into North Korea. It marked the second such test by the U.S. since its withdrawal from the Intermediate-Range Nuclear Forces(INF) Treaty earlier this year. 
Kim Bum-soo, KBS World Radio News.